Valving

ABSTRACT

A fluid valve comprising first and second interior chambers, a valve bore extending between the chambers, an exit port in a wall of the first chamber generally opposite the valve bore, a piston including a first portion slidably within the valve bore and, a second portion extending from the first portion to the exit port mounted for movement between a first position wherein the second portion overlies the exit port and a second position wherein the second portion is spaced from the exit port, the piston including also a bore extending therethrough and the first and second portions being of different cross-sectional areas, and a fixed balance pin extending from within the piston bore into the second chamber, the piston being slidable on the pin.

United States Patent [191 Denker [4 1 Feb. 26, 1974 [73] Assignee: Nutron Corporation, Hingham,

Mass.

[22] Filed: Mar. 1, 1972 [21 Appl. No.: 230,561

[52] U.S. Cl. 137/117, 91/417 [51] Int. Cl. [58] Field ofSearch ..l37/101,117,5l4.5,509, 137/514.3

[56] References Cited UNITED STATES PATENTS 3,389,796 6/1968 Fiala et a1. 137/509 X 3,114,380 12/1963 Allen 137/101 3,636,970 l/1972 Griffith et al.. 137/117 2,622,611 12/1952 Stark 4 137/117 X 1,804,751 5/1931 -Doble 137/117 2,445,544 7/1948 Trautman 137/117 2,791,229 5/1957 Pasco 137/117 3,115,923 12/1963 Kellner et al. 137/117 X FOREIGN PATENTS OR APPLICATIONS 592,721 5/1959 Italy l37/5l4.3

Primary Examiner-Robert G. Nilson [57] ABSTRACT A fluid valve comprising first and second interior chambers, a valve bore extending between the chambers, an exit port in a wall of the first chamber generally opposite the valve bore, a piston including a first portion slidably within the valve bore and, a second portion extending from the first portion to the exit port mounted for movement between a first position wherein the second portion overlies the exit port and a second position wherein the second portion is spaced from the exit port, the piston including also a bore extending therethrough and the first and second portions being of different cross-sectional areas, and a fixed balance pin extending from within the piston bore into the second chamber, the piston being slidable on the pin.

10 Claims, 5 DrawingFigures PATENTED 3 79-4 065 SNHET 1 BF 3 'PATENTEDFEBZBIBH 3.794.065

SHEEI 2 OF 3 'IIIIIIIII-IIH- VALVING This invention relates to valves.

It is a primary object of the present invention to provide a simple and inexpensive flow control valve that is the hydraulic equivalent of an electrical transistor. Other objects include providing pressure compensated valves in which the set flow rate can be varied from a remote-connection by changing an applied pilot pressure, and which with little or no modification are useful in a wide range of servo applications. I

The invention features a fluid valve comprising first and second interior chambers, an interior flow passage and a valve bore extending between the chambers, an exit port in a wall of the first chamber generally opposite the valve bore, a piston including a first portion slidably within the valve bore and, a second portion ex tending from the first portion to the exit port mounted for movement between a first position wherein the second portion overlies the exit port and asecond position wherein the second portion is spaced from the exit port, the piston including also a bore extending therethrough and the first and second portions being of different cross-sectional areas, and a fixed balance pin extending from within the piston bore into the second chamber, the piston being slidable on the pin. In preferred embodiments in which the piston, exit port, piston bore and balance pin are of circular cross section and the exit port is defined by a valve seat, there is featured a nose portion mounted in the end of the piston bore adjacent the exit port and including a damping orifice therethrough, a flow restrictor disposed in the flow passage, and a biaser comprising one of a spring and a pilot piston for bearing against the piston and biasing it one of toward and away from the exit port.

Other objects, features and advantages will appear from the following detailed description, taken together with the attached drawings, in which:

FIG. 1 is a plan sectional view of a valve embodying the invention;

.FIG. 2 is a plan sectional-view of portions of the valve of FIG. 1;

FIGS. 3 and 5 are plan sectional views of second and third valves embodying the invention; and,

FIG. 4 is a plan sectional, partially diagrammatic, view of a fourth valve embodying the invention, together with apparatus used therewith.

Referring more particularly to the drawings, there is shown in FIG. 1 a basic pressure compensating valve comprising a rectangular valve housing 12 in which thereare provided five drilled bores or conduits, each extending inwardly from a side wall of housing 12. As illustrated, bores l4, 16 which define respectively a valving chamber and a control conduit, extend parallel to each other in spaced relationship from housing end wall 18. Bores 20, 22 and 24 extend, parallel to each other and perpendicular to the axes of bores 14, 16, into housing 12 from housing side wall '26. Each of bores 20, 22 extends through valving chamber bore 14 to control conduit bore 16. Bore 24 extends to valve chamber bore 14, but does not intersect control conduit bore 16.

The portion of valve chamber bore 14 intersecting bores 20, 22 is of slightly greater diameter than that intersecting bore 24, providing an annular step between the two bore portions. An annular valve seat 28 having a drilled orifice 30 extending threrethrough coaxially with chamber bore 114 is seated on step 15, intermediate bores 22, 24. The end of chamber bore 14 adjacent end wall 18 is closed by a plug 32 having a coaxially cylindrical recess 34 in the inner end thereof.

A stepped cylindrical poppet piston 36 is closely-slip fitted within bore 14 with the smaller diameter portion 38 thereof adjacent valve seat 28 and the larger diameter portion 40 thereof intermediate bores 20, 22. A cylindrical bore 42 of diameter equal to that of orifice 30 extends coaxially through piston 36 and a piston nose 44 is fitted in the end of smaller diameter portion 38 in position for overlying and closing orifice 30 when piston 36 is seated against valve seat 28. A damping orifice 46 extends through nos'e 44. A cylindrical balance pin 48 one end of which is tightly slip fitted within piston bore 42, extends axially of chamber bore 14 from within piston 36 to within recess 34 of plug 32, where it is fixed by a transverse pin 50. As illustrated, the length and position of pin 48 are such that an internal chamber 52'is provided within piston bore 42 between nose 44 and the adjacent end of pin 48.

An axially adjustable needle valve 54 is threaded into control bore 16 to provide an annular adjustable reference orifice 56 between bores 20, 22. As shown, the reference orifice is defined by the cylindrical valving portions of bores 16, 20. Set screw 60 locks needle valve 54 in position.

Referring now to FIG. 2 which is an enlarged view of a portion of FIG. 1 with piston 36 slightly spaced from valve seat 28 for purpose of clarity it will be seen that the annular end 62 of piston 36 facing plug 32 has an area, A perpendicular to the piston axis, equal to the area of bore 14 less that of bore 42. End 62 is exposed to and worked on by fluid in bore 20. When piston 36 is closely adjacent valve seat 28, the other annular end 64 of piston major diameter portion 40 and the annular portion of rounded end 66 of nose 44 radially outward from valve seat orifice 30 are exposed to and worked on by fluid in bore 22. As valve seat orifice 30 and piston bore 42 are the same, the effective area, A perpendicular to the piston axis of the areas worked on by fluid in bore 22 is equal to area A,. After damping through orifice 46, fluid within orifice 30 will be equal to that within piston chamber 52, and the forces acting in opposite directions on opposite sides of piston nose 44 of diameter will be equal.

Accordingly, it will be seen that, after damping, the total force urging piston 36 toward seat 26 will be the product of area A, and the pressure within bore 20; the total force urging the piston away from the seat will be the product of area A and the pressure within bore 22. As the two areas are equal, the movement of the piston will depend entirely on the pressures in bores 20, 22 and not on that in bore 24. The damping provided by the orifice 46 in piston nose 44 insures stability.

As previously indicated, valve 10 is principally useful for passing a constant flow, regardless of the pressure of the fluid applied thereto. For such use, means are provided for applying a biasing force to piston 36 to urge it, depending on the desired use, toward or away from valve seat 28. FIGS. 3-5 illustrate three different valves designated 10a, 10b, 100, respectively, each of which is basically identical to valve lltl but includes additional components dependent on the desired end use. In each valve the respective portions identical to corresponding portions of valve 10 are identified by the same reference numbers, but with a difi'erentiating letter, a, b, or c, added thereto. In each valve, flow of fluid between bores 20, 22 through reference orifice 56 results in a pressure drop, causing the fluid in the upstream bore to be greater than that in the downstream bore. The pressure difference acts on the piston, urging it toward the lower pressure bore.

li e ferring now particularly to FIG. 3, v alve 1021 is a pilot governed pressure compensating valve and includes a pilot pressure bore 70 extending in coaxial alignment with chamber bore 14a from housing end wall 72 to chamber bore 14a. The outer portion 74 of pilot bore 70 is tapped to receive a fluid coupling. A pilot piston 76 is closely fitted in pilot bore 70 for axial movement therein; and a control rod 78, one end of which is press-fitted coaxially into the inner end of pilot piston 76, extends from the pilot piston through valve orifice 30a and bears against the end of piston nose 44.

In operation, bore 20a of valve 10a is an inlet conduit, bore 24a is an outlet conduit, and bore 22a is closed by plug 80. Fluid from inlet conduit bore 20a.

flows the length of the bore, through reference orifice 56a, into the portion of control bore 16a intermediate bores 20a, 22a, and thence into bore 240, through valve seat orifice 30a. A fluid pilot pressure is applied to the outer (spaced from piston 36a) end of pilot pi'ston 76. As is evident, the total force acting on piston 36a and urging it away from valve seat 28a is equal to that applied by pilot piston 76, plus that applied by the pressure P, of fluid in bore 22a to area A The total force urging the piston toward the seat is applied by the pressure P of fluid in bore 20a to area A For any set pilot pressure and reference orifice size, the rate of flow through the valve will stabilize at the rate such that the pressure drop, P,-P across reference orifice 56a is equal to force applied by pilot piston 76, F-,,,, divided by the effective piston area, A, or A The flow rate may be changed remotely simply by varying the pilot pressure.

The valve 10b illustrated in FIG. 4 differs from valve 10 in that bore 24b extends completely through valve housing 12b, from side 26b to side 81, helical compression spring 82 surrounds piston portion 38b with its opposite ends bearing against valve seat 28b and the axially-facing end 64b of piston major diameter portions 40b and bore 20b extends from side 81 rather than side 26b to permit the valve more conveniently to be connected, as shown, to a controlled fluid device such as doubleacting hydraulic actuator 83. Actuator 83 comprises a piston 84 within a cylinder 86 and having a piston rod 88 extending axially through one end of the cylinder. The area of the side 92 of piston 84 opposite rod 88 is twice that of the side 90 to which rod 88 is attached. A fluid line 94 connects the smaller area side of the actuator to bore 22b; line 96 connects the larger area side to bore 24b. Bore 24b is also connected, at side 81 of housing 12 b, to a line 98 leading from the bore through a variable orifice 100 to a fluid sump l02.

Spring 82 provides a constant force, F urging piston 36b away from valve seat 28b. When fluid is introduced into valve 10b through bore 20b, flow through reference orifice 56b will stabilize at a rate, Q0, such taht the pressure drop AP, across orifice 56b balances the biasing force F In the mode of operation shown in FIG. 4, fluid from a constant pressure source, at pressure P is introduced into valve b through bore b, and variable orifice 100 is adjusted as desired to control actuator 83. When orifice 100 is set to maintain a pressure P in bore 24b equal to one half that in bore 22b, P which is equal to P AP, the position of piston 84 within cylinder 96 is static and the entire flow 0 through reference orifice 56b passes through the valve to sump 102. Closing control orifice increases the pressure, P in bore 24b and causes piston 84 to move to the right (as shown in FIG. 4); opening orifice decreases pressure P causing the piston to move to the left.

Valve 10c, shown in FIG. 5, includes a pilot piston 76c arranged to urge piston 36c away from valve seat 280, and a helical spring surrounding balance pin 48c (with its opposite ends bearing against end 620 of piston major diameter portion 40c and plug 32c) urging the piston toward the valve seat. A relief pressure control bore 112 extends from housing end wall 72c, parallel with pilot bore 70c and coaxially with control bore 160, to control bore 16c. An internal conduit 114 extends from bore 112 to pilot bore 70c, the outer end of which is closed by a plug 116. A valve seal 118 having an orifice 120 extending axially therethrough is press fitted within relief bore 112 intermediate bore 22c and conduit 114. A relief pressure adjustment screw 122 is threaded into the outer portion of bore 112 for axial adjustment therein, and carries a poppet 124, one end of which is slip fitted within a coaxial cylindrical recess in the inner end 126 of screw 122 and the other end of which defines a conical closure 128 facing and arranged for closing orifice 120. A helical compression spring 130 surrounds poppet 124, with its opposite ends engaging the axially-facing surfaces of screw 122 and closure 128, urging the closure toward valve seat 118. Set screw 132 holds screw 122 in place.

In operation, bore 22c is connected to a constant flow, variable pressure supply source, such as a fixeddisplacement pump; bore 20c to a load; and bore 24c to a tank or sump. During normal flow, the pressure in pilot piston bore 700 and in relief pressure bore 112 is equal to that in bore 24c, and pilot piston 76c exerts no force on piston 36c. Flow through the valve stabilizes at a flow rate such that the pressure drop across reference orifice 56c balances the force exerted by spring 1 10. It should be noted that, unlike valves 10a and 10b, the pressure in bore 200 is less than that in bore 22c.

As with the other valves previously discussed, the rate of flow through reference orifice 56c will remain constant, regardless of variations in the absolute pressure of inlet fluid from the fluid source. To prevent too great a pressure being applied to the load, through bore 200, closure 128 opens whenever the pressure in bore 220 (which is equal to that in bore 20c plus the pressure drop across the reference orifice 56c) exceeds a predetermined level. This level is controlled by spring 130, and may be varied by adjusting adjustment screw 122. When closure 128 opens, high pressure fluid is applied to the left (viewed in FIG. 4) end of pilot piston 76c, forcing the pilot piston to drive piston 36c away from valve seat 28c, thereby relieving the pressure in bore 220 and, hence, in bore 20c also. As soon as the pressure in bore 22c drops below the predetermined level, closure 128 moves back against seat 118.

Other embodiments within the scope of the following claims will occur to those skilled in the art.

What is claimed is:

1. A fluid flow control valve comprising:

a housing defining first and second interior chambers, an interior flow passage and a valve bore each extending between said chambers, an inlet port, an inlet passage connecting said inlet port and one of said chambers, a first outlet port, an exit port in a wall of said first chamber generally opposite said valve bore, and a first outlet passage connecting said first outlet port and said exit port;

a piston including a first portion slidable within said valve bore and a second portion extending from said first portion toward said exit port, said piston being mounted for movement between a first position wherein said second portion overlies said exit port and a second position wherein said second portion is spaced from said exit port, and including a bore extending therethrough generally parallel to the direction of movement'thereof, said first and second portions being of different cross-sectional areas measured in respective parallel planes perpendicular to said direction of movement;

a biaser for biasing said piston one of toward and away from said exit port;

a fixed balance pin extending from within said piston bore into said second chamber, said piston being slidable on said pin; and

a flow restrictor disposed at least in part in said flow passage for controlling fluid flow therethrough,

the areas, measured in respective planes perpendicular to said direction of movement, of saidbalance pin and said exit port being equal, and

the effective areas, projected on respective planes generally perpendicular to said direction of movement, of the portion of said piston exposed to fluid in said second chamber, and of the portions of said piston exposed to fluid in said first chamber being equal when said piston is in said first position.

2. The valve of claim 1 wherein said biaser includes a spring mounted adjacent and bearing against said piston.

3. The valve of claim 1 wherein said biaser comprises a pilot bore, and means extending from within said pilot bore to adjacent said piston and including a pilot piston slidably mounted within said bore, said means being responsive to pressure of fluid within said pilot bore for bearing against said piston.

4. The valve of claim 1 including a relief passage extending from said first chamber and a valve disposed in said relief passage for preventing flow therethrough when pressure of fluid in said first chamber is below a predetermined level.

5. The valve of claim 4 including a pilot bore, a pilot piston disposed within said bore and including a member carried thereby extending through said exit port to adjacent said valve piston, and a conduit extending from said -relief passage to said pilot bore on the side of said pilot piston opposite said valve piston.

6. The valve of claim 1 wherein said piston, said piston bore, said exit port, said valve bore and said balance pin are coaxial, and the end of said piston adjacent said exit port includes a nose portion having a rounded end surface facing and arranged for overlying said exit port, said nose portion substantially closing an end of said piston bore and including a damping orifice extending coaxially therethrough.

7. The valve of claim 1 including a second outlet port and a second outlet passage connecting said second outlet port and the other of said chambers.

8. The valve of claim 7 wherein said inlet passage connects said inlet port and said second chamber, and

said second outlet passage connects said second outlet port and said first chamber, said biaser biasing said piston away from said exit port.

9. The valve of claim 8 including a third outlet port connected to said first outlet passage.

10. The valve of claim 8 wherein said biaser comprises a spring surrounding said second portion of said piston and biasing said piston away from said exit port with a predetermined force, whereby said piston is balanced when the force on said piston from fluid in said second chamber acting on said portions exposed to fluid in said second chamber is equal to the sum of the force on said piston of fluid in said first chamber acting on said portions exposed to fluid in said first chamber and said predetermined force. 

1. A fluid flow control valve comprising: a housing defining first and second interior chambers, an interior flow passage and a valve bore each extending between said chambers, an inlet port, an inlet passage connecting said inlet port and one of said chambers, a first outlet port, an exit port in a wall of said first chamber generally opposite said valve bore, and a first outlet passage connecting said first outlet port and said exit port; a piston including a first portion slidable within said valve bore and a second portion extending from said first portion toward said exit port, said piston being mounted for movement between a first position wherein said second portion overlies said exit port and a second position wherein said second portion is spaced from said exit port, and including a bore extending therethrough generally parallel to the direction of movement thereof, said first and second portions being of different cross-sectional areas measured in respective parallel planes perpendicular to said direction of movement; a biaser for biasing said piston one of toward and away from said exit port; a fixed balance pin extending from within said piston bore into said second chamber, said piston being slidable on said pin; and a flow restrictor disposed at least in part in said flow passage for controlling fluid flow therethrough, the areas, measured in respective planes perpendicular to said direction of movement, of said balance pin and said exit port being equal, and the effective areas, projected on respective planes generally perpendicular to said direction of movement, of the portion of said piston exposed to fluid in said second chamber, and of the portions of said piston exposed to fluid in said first chamber being equal when said piston is in said first position.
 2. The valve of claim 1 wherein said biaser includes a spring mounted adjacent and bearing against said piston.
 3. The valve of claim 1 wherein said biaser comprises a pilot bore, and means extending from within said pilot bore to adjacent said piston and including a pilot piston slidably mounted within said bore, said means being responsive to pressure of fluid within said pilot bore for bearing against said piston.
 4. The valve of claim 1 including a relief passage extending from said first chamber and a valve disposed in said relief passage for preventing flow therethrough when pressure of fluid in said first chamber is below a predetermined level.
 5. The valve of claim 4 including a pilot bore, a pilot piston disposed within said bore and including a member carried thereby extending through said exit port to adjacent said valve piston, and a conduit extending from said relief passage to said pilot bore on the side of said pilot piston opposite said valve piston.
 6. The valve of claim 1 wherein said piston, said piston bore, said exit port, said valve bore and said balance pin are coaxial, and the end of said piston adjacent said exit port includes a nose portion having a rounded end surface facing and arranged for overlying said exit port, said nose portion substantially closing an end of said piston bore and including a damping orifice extending coaxially therethrough.
 7. The valve of claim 1 including a second outlet port and a second outlet passage connecting said second outlet port and the other of said chambers.
 8. The valve of claim 7 wherein said inlet passage connects said inlet port and said second chamber, and said second outlet passage connects said second outlet port and said first chamber, said biaser biasing said piston away from said exit port.
 9. The valve of claim 8 including a third outlet port connected to said first outlet passage.
 10. The valve of claim 8 wherein said biaser comprises a spring surrounding said second portion of said piston and biasing said piston away from said exit port with a predetermined force, whereby saId piston is balanced when the force on said piston from fluid in said second chamber acting on said portions exposed to fluid in said second chamber is equal to the sum of the force on said piston of fluid in said first chamber acting on said portions exposed to fluid in said first chamber and said predetermined force. 